Recep Tayyip Erdoğan Üniversitesi Kurumsal Akademik Arşivi
DSpace@RTEÜ, Recep Tayyip Erdoğan Üniversitesi tarafından doğrudan ve dolaylı olarak yayınlanan; kitap, makale, tez, bildiri, rapor, araştırma verisi gibi tüm akademik kaynakları uluslararası standartlarda dijital ortamda depolar, Üniversitenin akademik performansını izlemeye aracılık eder, kaynakları uzun süreli saklar ve yayınların etkisini artırmak için telif haklarına uygun olarak Açık Erişime sunar.
Güncel Gönderiler
Drilling characteristics of additively manufactured pla/17-4 pH stainless steel hybrid composite: thrust force, surface roughness, vibration and temperature change
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Şentürk, Erhan; Alparslan, Cem; Ötüken, Ramazan; Erhan, Muhammed Furkan; Bayraktar, Şenol
Understanding the finishing behavior of hybrid structures produced by additive manufacturing based on FDM is critically important in systems where phases with different thermal and mechanical properties coexist. In this study, the drilling performance of hybrid structures with a PLA/17-4 PH/PLA layer arrangement was comprehensively investigated in terms of thrust force, moment, surface roughness, temperature variation, vibration behavior, and surface integrity. For this purpose, a total of 16 drilling tests were performed on 56 × 56 × 15 mm hybrid specimens with 100% infill density, in a full factorial configuration, at cutting speeds (V) of 80–170 m/min and feed rates (f) of 0.04–0.16 mm/rev. The middle layer was used in the as-printed green state as a 17-4 PH metal-filled filament containing metal particles and binder, without any debinding or sintering step. The results showed that increasing feed rate increased thrust force, moment, and surface roughness in all layers, whereas increasing cutting speed decreased these values and promoted a more stable drilling regime. The middle 17-4 PH layer exhibited lower surface roughness than the outer PLA layers, while thermal measurements indicated limited variation at the hole entrance and higher temperature accumulation at the hole exit. The most favorable drilling condition within the studied hybrid configuration was obtained at 170 m/min and 0.04 mm/rev, whereas the least favorable condition was obtained at 80 m/min and 0.16 mm/rev. Overall, the combination of high cutting speed and low feed rate provided the most suitable drilling window for the studied hybrid structure. The findings also indicated that surface quality was more strongly associated with cutting load and high-frequency vibration components than with vibration level alone.
When pain shapes dental anxiety: a cross-sectional mediation study in patients requiring endodontic treatment
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Maraş, Edanur; Başar, Özge; Çolakoğlu, İlyas
Objective: This study aimed to evaluate the associations between dental anxiety–fear, state–trait anxiety, and pain in patients requiring endodontic treatment and to explore the role of preoperative pain intensity in these associations. Methods: This cross-sectional study included 253 adults scheduled for endodontic treatment. Sociodemographic characteristics and relevant clinical data were recorded. Pain intensity and psychological variables were assessed using the Numerical Rating Scale (NRS), Modified Dental Anxiety Scale (MDAS), Dental Fear Survey (DFS), and the State Anxiety and Trait Anxiety subscales of the State–Trait Anxiety Inventory (STAI-S and STAI-T). Associations were analyzed using group comparison tests and correlation analyses, and mediation analyses were performed using Hayes’ PROCESS macro-4. Results: Significant correlations were found among all psychological parameters (p < 0.05). The observed associations were consistent with a potential partial mediating role of pain in the relationship between state–trait anxiety and dental anxiety. Higher anxiety levels were present in patients with anterior teeth requiring either primary treatment or retreatment compared with posterior teeth (p < 0.05). Conclusions: Preoperative pain may contribute to the association patterns identified between dental anxiety and state–trait anxiety. Further studies with larger sample sizes and adjusted analytical models are needed to better clarify these relationships.
Financial knowledge or managerial competence? Disentangling financial literacy and liquidity constraints for processing continuity and food security in the Turkish tea industry
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Gün, Musa; Savcı, Mustafa
The economic resilience of agricultural enterprises is increasingly relevant for maintaining processing continuity and food quality in highly perishable agro-food chains. This study examines the associations between financial knowledge, financial management competency, business liquidity, and operational food-processing continuity in Türkiye’s tea sector. A quantitative cross-sectional design was employed, using structured survey data from 203 senior managers across 86 public and private tea-processing firms in Rize Province. The data were analysed using Ordinary Least Squares regression, mediation analysis, exploratory factor analysis, and robustness checks in accordance with OECD/INFE guidelines. Results indicate a significant deficit in theoretical financial knowledge (mean score: 4.47/10) alongside widespread overconfidence among 85% of managers. Applied financial management competency is positively associated with perceived business liquidity (β = 0.336, p < 0.001), suggesting that practical budgeting, cash-flow planning, and financial decision-making capabilities are relevant to maintaining operational funding capacity. In contrast, cash-flow difficulties are not significantly explained by firm-level financial knowledge, managerial competency, liquidity, or ownership structure (R2 = 0.014, p = 0.722), indicating that these difficulties may reflect broader seasonal and sector-wide financing constraints. The findings challenge the assumption of a linear relationship between theoretical financial knowledge and managerial outcomes. They suggest a dual policy approach that combines applied financial management training with structural financing mechanisms to ensure the continuity of fresh leaf procurement and processing. While the study does not directly measure food safety, post-harvest losses, or SDG outcomes, the results have potential implications for reducing processing disruptions and supporting more resilient agro-food processing systems.
Linking tea aroma chemistry to quality grades via a single mos gas sensor: classical machine learning vs. Deep learning
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Taşdemir, Ahmet Turan; Özkat, Erkan Caner; Özkat, Gözde Yalçın; Gül, Fatih
Black tea quality is governed by aroma chemistry: terpene alcohols (linalool, geraniol, nerolidol), methyl salicylate, and short-chain aldehydes whose abundance and release kinetics from the polyphenol-rich leaf matrix shape perceived grade. Grade information lies not only in the average headspace concentration but in the temporal shape of volatile organic compound (VOC) release under controlled heating. Conventional electronic noses obscure this signal: they rely on multi-sensor arrays, compress each response into summary statistics, and report accuracy only at the level of individual measurements. Whether a single low-cost metal–oxide–semiconductor (MOS) gas sensor can recover grade-defining aroma chemistry, and whether waveform-level modeling can exploit it, was therefore investigated. A portable electronic nose built around a Bosch BME688 sensor recorded 90 time series, each comprising four directly measured channels (temperature, humidity, pressure, gas sensor resistance) and a derived indoor-air-quality (IAQ) proxy computed from them by the on-chip BSEC library, from 16 commercial Turkish black teas across three quality grades. Two representations were compared on the same data: a feature-based pipeline reducing 25 statistical descriptors to seven principal components for six classifiers (best F1-macro = 0.624, MLP), and a raw-waveform Multi-Scale 1D-CNN with Squeeze–Excitation and temporal self-attention (MS-CNN-Attention). Under product-grouped cross-validation, the deep model reached F1-macro = 0.811 (+30%) and graded 14 of 16 products correctly by majority vote, against 11 of 16 for the MLP, with the largest gain in the medium grade (F1: 0.52 → 0.79), where summary-statistic compression destroys the release-kinetic signal. The contributions are threefold: one programmable MOS sensor operated as a thermal-desorption profiler rather than a sensor array; a direct comparison of feature-based classical learning against raw-waveform deep learning on the same small, non-normally distributed dataset; and a product-level decision-consistency metric suited to batch screening. Pairing a low-cost MOS sensor with waveform-level modeling offers a rapid, non-destructive route to aroma-chemistry-based tea quality screening.
Comparison of the impact of different dacryocystorhinostomy techniques on patient quality of life in lacrimal duct obstruction
(Multidisciplinary Digital Publishing Institute (MDPI), 2026) Hakkani Öznay, Çağla; Fındık, Hüseyin; Uzun, Feyzahan; Kaim, Muhammet; Okutucu, Murat; Çeliker, Metin; Birinci, Mehmet
Objectives: To prospectively compare the outcomes of external dacryocystorhinostomy (EX-DCR), endonasal dacryocystorhinostomy (EN-DCR), and laser-assisted transcanalicular dacryocystorhinostomy (TL-DCR) in patients with nasolacrimal duct obstruction (NLDO) and to evaluate the relationship between surgical outcomes and patient quality of life (QoL). Methods: This prospective comparative study included patients presenting with epiphora who were diagnosed with NLDO and scheduled for surgical treatment. Patients underwent EX-DCR, EN-DCR, or TL-DCR according to patient preference and nasal anatomical characteristics. All patients received bicanalicular silicone tube intubation. Follow-up examinations were performed on postoperative day 1, week 1, at month 1, and every three months thereafter. Anatomical success was defined as patency on nasolacrimal irrigation, and functional success was defined as a postoperative Munk score of ≤ 1 (complete or near-complete resolution of epiphora). QoL was assessed using the Lacrimal Symptom Questionnaire (Lac-Q) and the Glasgow Benefit Inventory (GBI). Statistical comparisons were performed between groups. Results: A total of 69 patients (45 women, 24 men; mean age 58.99 ± 14.86 years) were included, with a mean follow-up of 17.19 ± 4.07 months. The highest postoperative pain scores were observed in the EX-DCR group; with no significant intergroup differences. Anatomical success rates were 92% for EX-DCR, 90.5% for EN-DCR, and 91.3% for TL-DCR. Functional success rates were 88%, 90.5%, and 82.7%, respectively, with no statistically significant difference among techniques (p > 0.05). All groups showed postoperative improvement in Lac-Q and GBI scores. Numerically greater improvements were observed in the EN-DCR group, although intergroup differences were not statistically significant. Conclusions: EX-DCR achieved the numerically highest anatomical success rate, whereas EN-DCR demonstrated numerically greater improvement in patient-reported QoL outcomes. However, no statistically significant differences in anatomical success, functional success, or QoL measures were observed among the three techniques. Overall, all three procedures were effective surgical options for the treatment of NLDO.
